The present invention relates to a vehicle chassis frame especially for heavy vehicles, such as for example trucks and similar freight vehicles.
In the construction of a heavy vehicle a chassis frame is the main structure of the vehicle onto which the other vehicle parts and equipments are attached. A vehicle chassis frame is commonly constructed of two parallel frame rails suitably interconnected by several transversal crossmembers in a ladder like way. The frame rails are usually C-shaped steel beams having a vertical web and horizontal upper and lower flanges; the said frame rails extend from the vehicle front end to the vehicle rear end.
A cabin, axles, suspension and wheels, an engine and a drive train can be attached onto the chassis at the front portion of the heavy vehicle. On the rear portion of the heavy vehicle, the chassis frame can receive one or more driving axles and wheels and corresponding vehicle suspensions; on the rear portion, a heavy vehicle can also be equipped with trailer connection means such as, for example, a fifth wheel or a superstructure such as, for example, a loading platform, a closed container for general cargo or bulk loads, a tank for liquid loads, a tipping device for refuse collection vehicles etc. The front portion and the rear portion of a heavy vehicle have therefore to face very different structural as well as functional issues.
Nevertheless, in most heavy vehicles the chassis frame exhibits a continuous structure from the vehicle front end to the vehicle rear end.
A chassis frame has to address different and sometimes contradictory issues. A vehicle front end usually incorporates bulky parts namely a vehicle engine and its corresponding cooling package that demand a wide chassis frame to accommodate the said bulky equipment. On the other hand, a vehicle rear end demands a narrow chassis frame as several parts such as for example a fuel tank, a battery box are laterally attached on the chassis frame; it should also be mentioned that the wheels (often tandem wheels on the rear axles) are also located on the outer side of the chassis frame.
From a functional viewpoint, the rear portion and the front portion of a heavy vehicle might have different layouts to address different vehicle uses. As far as the rear portion is concerned, parameters such as the number of rear axles, the type of the suspension (pneumatic), the length of the wheel base etc can vary from vehicle to vehicle. As far as the front portion in concerned parameters such as the cabin size, engine size etc can vary according to vehicle specifications A traditional ladder type chassis frame proves unable to adapt to the technical requirements of a vehicle front portion and rear portion.
Attempts to adapt a ladder type chassis to the contradictory specifications faced respectively by a vehicle front end and by a vehicle rear end have so far been largely unsuccessful. It has been proposed to widen the front end of a ladder chassis frame by outwardly cranking each frame rail. The extra cranking operation involves however a significant cost; considering the length of the frame rails that undergo a cranking phase, it may prove difficult to maintain acceptable tolerance; this also can weaken the frame rails. A further attempt to tackle the problem of varying the width of a chassis frame for heavy vehicles consists of having part or the entire chassis frame made of tubular elements instead of the existing frame rail. This solution is not economically viable as it requires a complete redesign of the entire spectrum of vehicular equipment. It therefore appears that there is room for improvement in heavy vehicle chassis architecture.
It is desirable to provide a vehicle chassis frame especially for heavy vehicles which can be of variable width and which obviates the disadvantages of the prior art.
It is desirable to provide a vehicle chassis frame that can be easily tailored in accordance with vehicle specifications. It is desirable to provide a vehicle chassis frame that is inexpensive to manufacture.
Thus, an aspect of the invention concerns a chassis frame for a heavy vehicle comprising a first chassis subsection having a first width w and, at least, a second frame subsection adjacent to the first chassis subsection having a width W greater than the width w of the first chassis subsection; each chassis subsection comprises a right and a left parallel C shaped frame rail inwardly open towards each other and extending longitudinally; the chassis further comprises a right—respectively left—interface bracket connecting two consecutive right—respectively left—frame rails belonging to two adjacent subsections; the said interface bracket maintains a transversal distance D between the said two consecutive right—respectively left—frame rails belonging to two adjacent subsections, and include at least one mounting unit onto which a vehicular part is secured.
The invention thus provides, according to an aspect thereof, a chassis frame which, in effect, can have at least two widths. Firstly, the invention provides a versatile chassis frame constructed of a number of subsections that can each have a specific width adapted to one or more specific vehicular functions. To achieve this, the chassis frame includes at least two interface brackets that can connect two consecutive frame rails while widening the chassis frame by maintaining a transversal distance between these frame rails. Importantly, each sub section is comprised of two parallel C shaped frame rails inwardly open towards each other which mean that the vertical web of each frame rail faces outwardly. On a practical level, this point proves to be of importance as a large number of already existing vehicular parts are designed to be fastened on the outward surface of the frame rail web where fastening holes can be easily provided and where upper and lower flanges do not interfere. Secondly the interface bracket is in itself capable of receiving at least one vehicular part; attaching a vehicular part onto the interface bracket can prove advantageous insofar as the said vehicular part is not directly attached onto the frame rail and thus the interface bracket absorbs vibrations that would otherwise be directly transmitted to the chassis frame.
In practical terms, each right—respectively left—interface bracket can be interposed between two right—respectively left—consecutive overlapping frame rails.
The critical element of the chassis frame i.e. the interface bracket whether right or left can comprise:                a central part that includes an array of spacing sleeves having a dimension D coinciding with an array of holes provided in a right—respectively left—frame rail and with an array of holes provided at the end of a subsequent right—respectively left—frame rail, and—at least one or more mounting units onto which a vehicular operational part can be secured.        
The interface bracket can include one or more mounting units of the group comprising:                a bearing provided in a lug extending downwards from the central part capable of receiving a suspension spring eye;        a mounting lug extending upwards from the central part;        a mounting lug extending downwards from the central part;        a mounting lug extending longitudinally from the central part;        a second array of holes, each extended by a flange ring capable of entering a second array of holes provided in the frame rails of the first chassis subsection.        
In concrete term, the first chassis subsection is a rear vehicle chassis subsection and the second chassis subsection is a front chassis subsection as the need for transversal space is more acute on the front end of a vehicle where vehicular parts such as an engine and a cooling package are accommodated and the need for a narrow chassis subsection is more acute on the rear end of a chassis where vehicular parts such as a fuel tank or a battery are commonly secured on the lateral side of the chassis frame.
Each frame rail of the first chassis subsection is made of a vertical web and an upper and a lower flange that can be provided with at least one cut to allow a passage for a mounting lug extending from the interface bracket.